MESOSCALE DISCUSSION 0082
NWS STORM PREDICTION CENTER NORMAN OK
1040 PM CST FRI FEB 20 2015
AREAS AFFECTED...CNTRL ILLINOIS...W-CNTRL INDIANA
CONCERNING...HEAVY SNOW
VALID 210440Z - 210745Z
SUMMARY...A NARROW BAND OF MODERATE TO HEAVY SNOW IS EXPECTED TO BE
SHORT-LIVED NEAR I-74 TO I-70 CORRIDORS. SNOWFALL RATES OF 1-2 IN/HR
SHOULD LAST THROUGH ABOUT 07-08Z.
DISCUSSION...W/E-ORIENTED PRECIPITATION BAND HAS PERSISTED OVER THE
PAST COUPLE HOURS ACROSS CNTRL IL. WHAT WAS INITIALLY LIGHT SNOW
WITH SOME MIXED PTYPES HAS TRANSITIONED TO MODERATE TO HEAVY SNOW
PER 04Z METARS AT KSPI AND KDEC. WITH THIS BAND LOCATED ON THE NRN
FRINGE OF ROBUST LOW-LEVEL WAA THAT WILL BECOME INCREASINGLY
CENTERED FROM THE MID-SOUTH TO OH/TN VALLEYS...SNOWFALL RATES WILL
LIKELY BE GREATEST IN THE NEXT FEW HOURS. EVENING MODEL GUIDANCE IS
CONSISTENT IN DEPICTING WANING WAA /AS LOW-LEVEL WINDS BECOME
INCREASINGLY VEERED/ WHERE THERMODYNAMIC PROFILES ARE ENTIRELY
SUPPORTIVE OF SNOW. MIXED PTYPES ARE ANTICIPATED TO PERSIST FOR
SEVERAL MORE HOURS FARTHER S /REF MCD 0081/. THE WRF-NSSL COMPOSITE
REFLECTIVITY BY PTYPE APPEARS REASONABLE WITH THE SNOW TO FREEZING
RAIN TRANSITION THIS EVENING AND IN SUGGESTING THE SHORT-LIVED
NATURE TO HEAVY SNOW.
..GRAMS.. 02/21/2015
ATTN...WFO...IND...ILX...LSX...
LAT...LON 40019005 40008852 40018762 39918683 39668681 39408705
39318779 39298853 39408979 39579015 39769030 40019005